Enemy Respawn

[NEGuy70]

I just started playing Bloodborne a few days ago and I finally got through the first area of central Yarnham where the main street with the bonfire is and all the enemies roaming up and down. I killed all of them and went into the next area where you can activate the short cut by dropping down by the kennels and going through the house to open up the gate by the lamp. When I went back down to head over to the new area where the fountain plaza is, that whole street was repopulated with all of the original enemies again. I did not die or go back to the Hunters Dream during any of it so why the respawn? I had watched some YouTube videos of the same area and all of the original enemies stayed dead. Did an update change this? Is this normal?